1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to an LCD device having a pad with a fine pitch so as to decrease the size of a pad and a data TCP for a data driver.
2. Discussion of the Related Art
Demands for various display devices have increased with the development and growth of an information society. Accordingly, many efforts have been made to research and develop various flat display devices such as liquid crystal displays (LCD), plasma display panels (PDP), electroluminescent displays (ELD), and vacuum fluorescent displays (VFD). Some types of flat display devices have already been applied to displays for various equipment.
Among the various flat display devices, liquid crystal display (LCD) devices have been most widely used due to advantageous characteristics such as a thin profile, low weight, and low power consumption, whereby the LCD devices provide a substitute for a cathode ray tube (CRT). In addition to mobile type LCD devices such as a display for a notebook computer, LCD devices have been developed for computer monitors and televisions to receive and display broadcast signals.
Hereinafter, a related art LCD device will be explained with reference to the accompanying drawings.
FIG. 1 is a layout illustrating an LCD device according to the related art. FIG. 2 is a detailed view illustrating a pitch of a data driving unit according to the related art.
As shown in FIGS. 1 and 2, a related art LCD device includes an LCD panel 20 that includes: lower and upper substrates 10 and 11 and a liquid crystal layer (not shown) formed between the lower and upper substrates 10 and 11; a gate driving unit 12 that includes a plurality of gate drivers connected with the lower substrate 11; a data driving unit 15 that includes a plurality of data drivers connected between a source PCB 14 and the lower substrate 11 by respective data TCPs 13; and a seal line 16 formed in the circumference of the lower and upper substrates 10 and 11 to bond the lower and upper substrates 10 and 11 to each other.
The gate driving unit 12 and the data driver unit 15 include a plurality of TCP mounted respective drivers and connected with the lower substrate 11.
Also, a timing controller (not shown) is provided so as to output control signals and video information to the gate driving unit 12 and the data driving unit 15.
The LCD panel 20 includes a pixel area 21 for displaying images.
Also, the lower substrate 11 of the LCD panel 20 includes: a plurality of gate and data lines; a plurality of pixel electrodes; and a plurality of thin film transistors TFTs. In this case, the gate lines cross the data lines to thereby define pixel regions in a matrix configuration. Then, the pixel electrodes are respectively formed in the pixel regions. The plurality of thin film transistors TFTs are formed adjacent to crossing areas of the gate and data lines, wherein each of the thin film transistors TFTs applies a signal of the data line to each of the pixel electrodes according to a signal of the gate line.
The thin film transistor TFT includes a gate electrode protruding from one side of the gate line; a gate insulating layer formed on an entire surface of the lower substrate 11; an active layer overlapped with the gate electrode; a source electrode overlapped with one side of the data line and one side of the gate electrode; and a drain electrode formed at a predetermined interval from the source electrode.
In addition, a passivation layer is formed on the lower substrate 11, wherein the passivation layer has a first contact hole corresponding to the drain electrode. That is, the drain electrode is electrically connected with the pixel electrode by the first contact hole.
Although not shown, the upper substrate 10 includes: a black matrix layer; a color filter layer formed corresponding to the pixel regions; and a common electrode formed corresponding to the pixel electrode.
Then, liquid crystal is provided between the upper and lower substrates 10 and 11. As a voltage is applied to the common electrode and the pixel electrode, the liquid crystal is driven.
Also, a data pad unit 19 is provided in the data TCP 13 of the data driving unit 15, wherein the data pad unit 19 transmits the data signal to the data line of the LCD panel 20.
As show in FIG. 2, the data pad unit 19 has the same pitch on each data TCP 18. That is, the data pad unit 19 is provided with a plurality of data pads 23, wherein the data pads 23 are provided at the same width and interval.
In the drawings, reference number ‘18’ corresponds to a data chip.
However, if the data pads 19 are formed with the same pitch, and each data TCP 13 of the data driving unit 15 is bonded to the pad of the lower substrate 11, it may be misaligned when bonding the lower substrate 11 due to the difference of expansion in the data pad unit 19.
To decrease manufacturing costs, it is necessary to decrease each data TCP 13 of the data driving unit 15 in size and to decrease each pad of the data pad unit 19 in size.
However, if decreasing both the width and interval of the data pad, it may have a short due to the misalignment when bonding the data pad to the LCD panel.
In this respect, it is impossible to infinitely decrease the width and interval of the data pad with current process cababilities.